High-quality media, e.g. in the pharmaceutical area, or aggressive media must be dosed with high accuracy e.g. for test laboratories or also in production processes. The quantities to be dosed in part are extremely small, e.g. in the single-digit μl range. For this purpose, syringe pumps, diaphragm pumps or peristaltic pumps usually are employed. Depending on their construction, these types of pump have advantages and disadvantages. Syringe pumps for example are expensive due to the required electronic actuation and are not able to deliver continuously. Peristaltic pumps and diaphragm pumps often are not accurate enough for precise dosing. From DE 20 2012 003 948 U1 there is known a dosing device which employs a diaphragm pump. Before and after the dosing chamber diaphragm valves are configured in the inflow channel and in the outlet channel, which can be actuated pneumatically, in order to limit the fluid quantity supplied to the diaphragm pump. The pneumatic back pressure which so far has occurred in such dosing devices when ejecting the fluid from the dosing chamber does not lead to a problem in this dosing device, because the upstream diaphragm valve closes safely.
It is the object of the invention to create a dosing device which is constructed very simple and nevertheless provides for safe dosing reliable above all over an extended period.